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0db7bc633d895212fa724a3ed4999a4b4d09a12c
android/libwvdrmengine/oemcrypto/mock/src/oemcrypto_session.cpp
Fred Gylys-Colwell 1e451340ba Fix SRM Version in mock 
Merge from Widevine repo of http://go/wvgerrit/26522

The modifiable OEMCrypto mock did not use the correct initial SRM
version as specified in the options file.  This CL fixes that.

b/37713658

Change-Id: I5ab5f5549dd7815edd4a3d69b804440faedeb657
2017-05-01 14:42:48 -07:00

1329 lines
48 KiB
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// Copyright 2017 Google Inc. All Rights Reserved.
//
// Mock implementation of OEMCrypto APIs
//
#include "oemcrypto_session.h"
#include <arpa/inet.h>
#include <assert.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <vector>
#include <openssl/aes.h>
#include <openssl/bio.h>
#include <openssl/cmac.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/rand.h>
#include <openssl/rsa.h>
#include <openssl/sha.h>
#include <openssl/x509.h>
#include "keys.h"
#include "log.h"
#include "oemcrypto_engine_mock.h"
#include "oemcrypto_key_mock.h"
#include "oemcrypto_logging.h"
#include "oemcrypto_rsa_key_shared.h"
#include "string_conversions.h"
#include "wv_cdm_constants.h"
static const int kPssSaltLength = 20;
namespace {
// Increment counter for AES-CTR. The CENC spec specifies we increment only
// the low 64 bits of the IV counter, and leave the high 64 bits alone.
void ctr128_inc64(uint8_t* counter) {
uint32_t n = 16;
do {
if (++counter[--n] != 0) return;
} while (n > 8);
}
void dump_openssl_error() {
while (unsigned long err = ERR_get_error()) {
char buffer[120];
LOGE("openssl error -- %lu -- %s", err, ERR_error_string(err, buffer));
}
}
} // namespace
namespace wvoec_mock {
SessionContext::~SessionContext() {
if (usage_entry_) {
delete usage_entry_;
usage_entry_ = NULL;
}
}
// Internal utility function to derive key using CMAC-128
bool SessionContext::DeriveKey(const std::vector<uint8_t>& key,
const std::vector<uint8_t>& context, int counter,
std::vector<uint8_t>* out) {
if (key.empty() || counter > 4 || context.empty() || out == NULL) {
LOGE("[DeriveKey(): OEMCrypto_ERROR_INVALID_CONTEXT]");
return false;
}
const EVP_CIPHER* cipher = EVP_aes_128_cbc();
CMAC_CTX* cmac_ctx = CMAC_CTX_new();
if (!CMAC_Init(cmac_ctx, &key[0], key.size(), cipher, 0)) {
LOGE("[DeriveKey(): OEMCrypto_ERROR_CMAC_FAILURE]");
return false;
}
std::vector<uint8_t> message;
message.push_back(counter);
message.insert(message.end(), context.begin(), context.end());
if (!CMAC_Update(cmac_ctx, &message[0], message.size())) {
LOGE("[DeriveKey(): OEMCrypto_ERROR_CMAC_FAILURE]");
return false;
}
size_t reslen;
uint8_t res[128];
if (!CMAC_Final(cmac_ctx, res, &reslen)) {
LOGE("[DeriveKey(): OEMCrypto_ERROR_CMAC_FAILURE]");
return false;
}
out->assign(res, res + reslen);
CMAC_CTX_free(cmac_ctx);
return true;
}
bool SessionContext::DeriveKeys(const std::vector<uint8_t>& master_key,
const std::vector<uint8_t>& mac_key_context,
const std::vector<uint8_t>& enc_key_context) {
// Generate derived key for mac key
std::vector<uint8_t> mac_key_server;
std::vector<uint8_t> mac_key_client;
std::vector<uint8_t> mac_key_part2;
if (!DeriveKey(master_key, mac_key_context, 1, &mac_key_server)) {
return false;
}
if (!DeriveKey(master_key, mac_key_context, 2, &mac_key_part2)) {
return false;
}
mac_key_server.insert(mac_key_server.end(), mac_key_part2.begin(),
mac_key_part2.end());
if (!DeriveKey(master_key, mac_key_context, 3, &mac_key_client)) {
return false;
}
if (!DeriveKey(master_key, mac_key_context, 4, &mac_key_part2)) {
return false;
}
mac_key_client.insert(mac_key_client.end(), mac_key_part2.begin(),
mac_key_part2.end());
// Generate derived key for encryption key
std::vector<uint8_t> enc_key;
if (!DeriveKey(master_key, enc_key_context, 1, &enc_key)) {
return false;
}
if (LogCategoryEnabled(kLoggingDumpDerivedKeys)) {
LOGI((" mac_key_context = " + wvcdm::b2a_hex(mac_key_context)).c_str());
LOGI((" enc_key_context = " + wvcdm::b2a_hex(enc_key_context)).c_str());
LOGI((" mac_key_server = " + wvcdm::b2a_hex(mac_key_server)).c_str());
LOGI((" mac_key_client = " + wvcdm::b2a_hex(mac_key_client)).c_str());
LOGI((" enc_key = " + wvcdm::b2a_hex(enc_key)).c_str());
}
set_mac_key_server(mac_key_server);
set_mac_key_client(mac_key_client);
set_encryption_key(enc_key);
return true;
}
bool SessionContext::RSADeriveKeys(
const std::vector<uint8_t>& enc_session_key,
const std::vector<uint8_t>& mac_key_context,
const std::vector<uint8_t>& enc_key_context) {
if (!rsa_key()) {
LOGE("[RSADeriveKeys(): no RSA key set]");
return false;
}
if (enc_session_key.size() != static_cast<size_t>(RSA_size(rsa_key()))) {
LOGE("[RSADeriveKeys(): encrypted session key wrong size:%zu, expected %d]",
enc_session_key.size(), RSA_size(rsa_key()));
dump_openssl_error();
return false;
}
session_key_.resize(RSA_size(rsa_key()));
int decrypted_size =
RSA_private_decrypt(enc_session_key.size(), &enc_session_key[0],
&session_key_[0], rsa_key(), RSA_PKCS1_OAEP_PADDING);
if (-1 == decrypted_size) {
LOGE("[RSADeriveKeys(): error decrypting session key.]");
dump_openssl_error();
return false;
}
session_key_.resize(decrypted_size);
if (decrypted_size != static_cast<int>(wvcdm::KEY_SIZE)) {
LOGE("[RSADeriveKeys(): error. Session key is wrong size: %d.]",
decrypted_size);
dump_openssl_error();
session_key_.clear();
return false;
}
return DeriveKeys(session_key_, mac_key_context, enc_key_context);
}
// Utility function to generate a message signature
bool SessionContext::GenerateSignature(const uint8_t* message,
size_t message_length,
uint8_t* signature,
size_t* signature_length) {
if (message == NULL || message_length == 0 || signature == NULL ||
signature_length == 0) {
LOGE("[OEMCrypto_GenerateSignature(): OEMCrypto_ERROR_INVALID_CONTEXT]");
return false;
}
if (mac_key_client_.empty() ||
mac_key_client_.size() != wvcdm::MAC_KEY_SIZE) {
LOGE("[GenerateSignature(): No MAC Key]");
return false;
}
if (*signature_length < SHA256_DIGEST_LENGTH) {
*signature_length = SHA256_DIGEST_LENGTH;
return false;
}
unsigned int md_len = *signature_length;
if (HMAC(EVP_sha256(), &mac_key_client_[0], mac_key_client_.size(), message,
message_length, signature, &md_len)) {
*signature_length = md_len;
return true;
}
return false;
}
size_t SessionContext::RSASignatureSize() {
if (!rsa_key()) {
LOGE("[GenerateRSASignature(): no RSA key set]");
return 0;
}
return static_cast<size_t>(RSA_size(rsa_key()));
}
OEMCryptoResult SessionContext::GenerateRSASignature(
const uint8_t* message, size_t message_length, uint8_t* signature,
size_t* signature_length, RSA_Padding_Scheme padding_scheme) {
if (message == NULL || message_length == 0 || signature == NULL ||
signature_length == 0) {
LOGE("[GenerateRSASignature(): OEMCrypto_ERROR_INVALID_CONTEXT]");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if (!rsa_key()) {
LOGE("[GenerateRSASignature(): no RSA key set]");
return OEMCrypto_ERROR_INVALID_RSA_KEY;
}
if (*signature_length < static_cast<size_t>(RSA_size(rsa_key()))) {
*signature_length = RSA_size(rsa_key());
return OEMCrypto_ERROR_SHORT_BUFFER;
}
if ((padding_scheme & allowed_schemes_) != padding_scheme) {
LOGE("[GenerateRSASignature(): padding_scheme not allowed]");
return OEMCrypto_ERROR_INVALID_RSA_KEY;
}
// This is the standard padding scheme used for license requests.
if (padding_scheme == kSign_RSASSA_PSS) {
// Hash the message using SHA1.
uint8_t hash[SHA_DIGEST_LENGTH];
if (!SHA1(message, message_length, hash)) {
LOGE("[GeneratRSASignature(): error creating signature hash.]");
dump_openssl_error();
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
// Add PSS padding.
std::vector<uint8_t> padded_digest(*signature_length);
int status = RSA_padding_add_PKCS1_PSS_mgf1(
rsa_key(), &padded_digest[0], hash, EVP_sha1(), NULL, kPssSaltLength);
if (status == -1) {
LOGE("[GeneratRSASignature(): error padding hash.]");
dump_openssl_error();
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
// Encrypt PSS padded digest.
status = RSA_private_encrypt(*signature_length, &padded_digest[0],
signature, rsa_key(), RSA_NO_PADDING);
if (status == -1) {
LOGE("[GeneratRSASignature(): error in private encrypt.]");
dump_openssl_error();
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
// This is the alternate padding scheme used by cast receivers only.
} else if (padding_scheme == kSign_PKCS1_Block1) {
if (message_length > 83) {
LOGE("[GeneratRSASignature(): RSA digest too large.]");
return OEMCrypto_ERROR_SIGNATURE_FAILURE;
}
// Pad the message with PKCS1 padding, and then encrypt.
size_t status = RSA_private_encrypt(message_length, message, signature,
rsa_key(), RSA_PKCS1_PADDING);
if (status != *signature_length) {
LOGE("[GeneratRSASignature(): error in RSA private encrypt. status=%d]",
status);
dump_openssl_error();
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
} else { // Bad RSA_Padding_Scheme
return OEMCrypto_ERROR_INVALID_RSA_KEY;
}
return OEMCrypto_SUCCESS;
}
// Validate message signature
bool SessionContext::ValidateMessage(const uint8_t* given_message,
size_t message_length,
const uint8_t* given_signature,
size_t signature_length) {
if (signature_length != SHA256_DIGEST_LENGTH) {
return false;
}
uint8_t computed_signature[SHA256_DIGEST_LENGTH];
memset(computed_signature, 0, SHA256_DIGEST_LENGTH);
unsigned int md_len = SHA256_DIGEST_LENGTH;
if (!HMAC(EVP_sha256(), &mac_key_server_[0], mac_key_server_.size(),
given_message, message_length, computed_signature, &md_len)) {
LOGE("ValidateMessage: Could not compute signature.");
return false;
}
if (memcmp(given_signature, computed_signature, signature_length)) {
LOGE("Invalid signature given: %s",
wvcdm::HexEncode(given_signature, signature_length).c_str());
LOGE("Invalid signature computed: %s",
wvcdm::HexEncode(computed_signature, signature_length).c_str());
return false;
}
return true;
}
OEMCryptoResult SessionContext::CheckStatusOnline(uint32_t nonce,
uint32_t control) {
if (!(control & kControlNonceEnabled)) {
LOGE("LoadKeys: Server provided Nonce_Required but Nonce_Enabled = 0.");
// Server error. Continue, and assume nonce required.
}
if (!CheckNonce(nonce)) return OEMCrypto_ERROR_INVALID_NONCE;
switch (usage_entry_status_) {
case kNoUsageEntry:
LOGE("LoadKeys: Session did not create usage entry.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
case kUsageEntryLoaded:
LOGE("LoadKeys: Session reloaded existing entry.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
case kUsageEntryNew:
return OEMCrypto_SUCCESS;
default: // invalid status.
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
}
OEMCryptoResult SessionContext::CheckStatusOffline(uint32_t nonce,
uint32_t control) {
if (control & kControlNonceEnabled) {
LOGE("KCB: Server provided NonceOrEntry but Nonce_Enabled = 1.");
// Server error. Continue, and assume nonce required.
}
switch (usage_entry_status_) {
case kNoUsageEntry:
LOGE("LoadKeys: Session did not create or load usage entry.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
case kUsageEntryLoaded:
// Repeat load. Calling function will verify pst and keys.
return OEMCrypto_SUCCESS;
case kUsageEntryNew:
// First load. Verify nonce.
if (!CheckNonce(nonce)) return OEMCrypto_ERROR_INVALID_NONCE;
return OEMCrypto_SUCCESS;
default: // invalid status.
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
}
OEMCryptoResult SessionContext::CheckNonceOrEntry(
const KeyControlBlock& key_control_block) {
switch (key_control_block.control_bits() & kControlReplayMask) {
case kControlNonceRequired: // Online license. Nonce always required.
return CheckStatusOnline(key_control_block.nonce(),
key_control_block.control_bits());
break;
case kControlNonceOrEntry: // Offline license. Nonce required on first use.
return CheckStatusOffline(key_control_block.nonce(),
key_control_block.control_bits());
break;
default:
if ((key_control_block.control_bits() & kControlNonceEnabled) &&
(!CheckNonce(key_control_block.nonce()))) {
LOGE("LoadKeys: BAD Nonce");
return OEMCrypto_ERROR_INVALID_NONCE;
}
}
return OEMCrypto_SUCCESS;
}
void SessionContext::StartTimer() { timer_start_ = time(NULL); }
uint32_t SessionContext::CurrentTimer() {
time_t now = time(NULL);
return now - timer_start_;
}
OEMCryptoResult SessionContext::LoadKeys(
const uint8_t* message, size_t message_length, const uint8_t* signature,
size_t signature_length, const uint8_t* enc_mac_key_iv,
const uint8_t* enc_mac_keys, size_t num_keys,
const OEMCrypto_KeyObject* key_array, const uint8_t* pst,
size_t pst_length, const uint8_t* srm_requirement) {
// Validate message signature
if (!ValidateMessage(message, message_length, signature, signature_length)) {
return OEMCrypto_ERROR_SIGNATURE_FAILURE;
}
StartTimer();
if (srm_requirement) {
const std::string kSRMVerificationString = "HDCPDATA";
if (memcmp(srm_requirement, kSRMVerificationString.c_str(),
kSRMVerificationString.size())) {
LOGE("SRM Requirement Data has bad verification string: %8s",
srm_requirement);
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
uint32_t minimum_version =
htonl(*reinterpret_cast<const uint32_t*>(srm_requirement + 8));
uint16_t current_version = 0;
if (OEMCrypto_SUCCESS != ce_->current_srm_version(&current_version)) {
LOGW("[LoadKeys: SRM Version not available.");
srm_requirements_status_ = InvalidSRMVersion;
} else if (current_version < minimum_version) {
LOGW("[LoadKeys: SRM Version is too small %d, required: %d",
current_version, minimum_version);
srm_requirements_status_ = InvalidSRMVersion;
} else if (ce_->srm_blacklisted_device_attached()) {
LOGW("[LoadKeys: SRM blacklisted device attached]");
srm_requirements_status_ = InvalidSRMVersion;
} else {
srm_requirements_status_ = ValidSRMVersion;
}
}
// If there are already keys installed in this session, then we can load
// a shared license.
bool second_license = (session_keys_.size() > 0);
// Decrypt and install keys in key object
// Each key will have a key control block. They will all have the same nonce.
OEMCryptoResult status = OEMCrypto_SUCCESS;
std::vector<uint8_t> key_id;
std::vector<uint8_t> enc_key_data;
std::vector<uint8_t> key_data_iv;
std::vector<uint8_t> key_control;
std::vector<uint8_t> key_control_iv;
for (unsigned int i = 0; i < num_keys; i++) {
key_id.assign(key_array[i].key_id,
key_array[i].key_id + key_array[i].key_id_length);
enc_key_data.assign(key_array[i].key_data,
key_array[i].key_data + key_array[i].key_data_length);
key_data_iv.assign(key_array[i].key_data_iv,
key_array[i].key_data_iv + wvcdm::KEY_IV_SIZE);
if (key_array[i].key_control == NULL) {
status = OEMCrypto_ERROR_UNKNOWN_FAILURE;
break;
}
key_control.assign(key_array[i].key_control,
key_array[i].key_control + wvcdm::KEY_CONTROL_SIZE);
key_control_iv.assign(key_array[i].key_control_iv,
key_array[i].key_control_iv + wvcdm::KEY_IV_SIZE);
OEMCryptoResult result = InstallKey(
key_id, enc_key_data, key_data_iv, key_control, key_control_iv,
key_array[i].cipher_mode == OEMCrypto_CipherMode_CTR, second_license);
if (result != OEMCrypto_SUCCESS) {
status = result;
break;
}
}
FlushNonces();
if (status != OEMCrypto_SUCCESS) return status;
// enc_mac_key can be NULL if license renewal is not supported
if (enc_mac_keys != NULL) {
// V2.1 license protocol: update mac keys after processing license response
const std::vector<uint8_t> enc_mac_keys_str = std::vector<uint8_t>(
enc_mac_keys, enc_mac_keys + 2 * wvcdm::MAC_KEY_SIZE);
const std::vector<uint8_t> enc_mac_key_iv_str = std::vector<uint8_t>(
enc_mac_key_iv, enc_mac_key_iv + wvcdm::KEY_IV_SIZE);
if (!UpdateMacKeys(enc_mac_keys_str, enc_mac_key_iv_str)) {
LOGE("Failed to update mac keys.\n");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
}
if (usage_entry_) {
OEMCryptoResult result = OEMCrypto_SUCCESS;
switch (usage_entry_status_) {
case kNoUsageEntry:
if (pst_length > 0) {
LOGE("LoadKeys: PST specified but no usage entry loaded.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
break; // no extra check.
case kUsageEntryNew:
result = usage_entry_->SetPST(pst, pst_length);
if (result != OEMCrypto_SUCCESS) {
return result;
}
if (!usage_entry_->SetMacKeys(mac_key_server_, mac_key_client_)) {
LOGE("LoadKeys: Usage table can't set keys.\n");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
break;
case kUsageEntryLoaded:
if (!usage_entry_->VerifyPST(pst, pst_length)) {
return OEMCrypto_ERROR_WRONG_PST;
}
if (!usage_entry_->VerifyMacKeys(mac_key_server_, mac_key_client_)) {
LOGE("LoadKeys: Usage table entry mac keys do not match.\n");
return OEMCrypto_ERROR_WRONG_KEYS;
}
if (usage_entry_->Inactive()) return OEMCrypto_ERROR_LICENSE_INACTIVE;
break;
}
}
return OEMCrypto_SUCCESS;
}
OEMCryptoResult SessionContext::InstallKey(
const KeyId& key_id, const std::vector<uint8_t>& key_data,
const std::vector<uint8_t>& key_data_iv,
const std::vector<uint8_t>& key_control,
const std::vector<uint8_t>& key_control_iv, bool ctr_mode,
bool second_license) {
// Decrypt encrypted key_data using derived encryption key and offered iv
std::vector<uint8_t> content_key;
std::vector<uint8_t> key_control_str;
if (!DecryptMessage(encryption_key_, key_data_iv, key_data, &content_key)) {
LOGE("[Installkey(): Could not decrypt key data]");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (LogCategoryEnabled(kLoggingDumpContentKeys)) {
LOGI((" InstallKey: key_id = " +
wvcdm::b2a_hex(key_id)).c_str());
LOGI((" InstallKey: content_key = " +
wvcdm::b2a_hex(content_key)).c_str());
LOGI((" InstallKey: key_control = " +
wvcdm::b2a_hex(key_control_str)).c_str());
}
// Key control must be supplied by license server
if (key_control.empty()) {
LOGE("[Installkey(): WARNING: No Key Control]");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if (key_control_iv.empty()) {
LOGE("[Installkey(): ERROR: No Key Control IV]");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if (!DecryptMessage(content_key, key_control_iv, key_control,
&key_control_str)) {
LOGE("[Installkey(): ERROR: Could not decrypt content key]");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Key ID: %s", wvcdm::b2a_hex(key_id).c_str());
}
KeyControlBlock key_control_block(key_control_str);
if (!key_control_block.valid()) {
LOGE("Error parsing key control.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if ((key_control_block.control_bits() &
kControlRequireAntiRollbackHardware) &&
!ce_->config_is_anti_rollback_hw_present()) {
LOGE("Anti-rollback hardware is required but hardware not present.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
uint8_t minimum_patch_level =
(key_control_block.control_bits() & kControlSecurityPatchLevelMask) >>
kControlSecurityPatchLevelShift;
if (minimum_patch_level > OEMCrypto_Security_Patch_Level()) {
LOGE("[InstallKey(): security patch level: %d. Minimum:%d]",
OEMCrypto_Security_Patch_Level(), minimum_patch_level);
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
OEMCryptoResult result = CheckNonceOrEntry(key_control_block);
if (result != OEMCrypto_SUCCESS) {
LOGE("LoadKeys: Failed Nonce/PST check.");
return result;
}
if (key_control_block.control_bits() & kSharedLicense) {
if (!second_license) {
LOGE("LoadKeys: Shared License, but no keys previously loaded.");
return OEMCrypto_ERROR_MISSING_MASTER;
}
}
if (key_control_block.control_bits() & kControlSRMVersionRequired) {
if (srm_requirements_status_ == NoSRMVersion) {
LOGE("[LoadKeys: control bit says SRM version required]");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if (srm_requirements_status_ == InvalidSRMVersion) {
// If the SRM version is too small, treat this key as local display only.
key_control_block.RequireLocalDisplay();
}
}
Key key(content_key, key_control_block, ctr_mode);
session_keys_.Insert(key_id, key);
return OEMCrypto_SUCCESS;
}
bool SessionContext::InstallRSAEncryptedKey(
const uint8_t* encrypted_message_key, size_t encrypted_message_key_length) {
encryption_key_.resize(RSA_size(rsa_key()));
int decrypted_size = RSA_private_decrypt(
encrypted_message_key_length, encrypted_message_key, &encryption_key_[0],
rsa_key(), RSA_PKCS1_OAEP_PADDING);
if (-1 == decrypted_size) {
LOGE("[RSADeriveKeys(): error decrypting session key.]");
dump_openssl_error();
return false;
}
encryption_key_.resize(decrypted_size);
if (decrypted_size != static_cast<int>(wvcdm::KEY_SIZE)) {
LOGE("[RSADeriveKeys(): error. Session key is wrong size: %d.]",
decrypted_size);
dump_openssl_error();
encryption_key_.clear();
return false;
}
return true;
}
OEMCryptoResult SessionContext::RefreshKey(
const KeyId& key_id, const std::vector<uint8_t>& key_control,
const std::vector<uint8_t>& key_control_iv) {
if (key_id.empty()) {
// Key control is not encrypted if key id is NULL
KeyControlBlock key_control_block(key_control);
if (!key_control_block.valid()) {
LOGE("Parse key control error.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if ((key_control_block.control_bits() & kControlNonceEnabled) &&
(!CheckNonce(key_control_block.nonce()))) {
LOGE("KCB: BAD Nonce");
return OEMCrypto_ERROR_INVALID_NONCE;
}
// Apply duration to all keys in this session
session_keys_.UpdateDuration(key_control_block);
return OEMCrypto_SUCCESS;
}
Key* content_key = session_keys_.Find(key_id);
if (NULL == content_key) {
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Error: no matching content key.");
}
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (key_control.empty()) {
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Error: no key_control.");
}
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
const std::vector<uint8_t> content_key_value = content_key->value();
// Decrypt encrypted key control block
std::vector<uint8_t> control;
if (key_control_iv.empty()) {
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Key control block is NOT encrypted.");
}
control = key_control;
} else {
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Key control block is encrypted.");
}
if (!DecryptMessage(content_key_value, key_control_iv, key_control,
&control)) {
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Error decrypting key control block.");
}
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
}
KeyControlBlock key_control_block(control);
if (!key_control_block.valid()) {
if (LogCategoryEnabled(kLoggingDumpKeyControlBlocks)) {
LOGD("Parse key control error.");
}
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
if ((key_control_block.control_bits() & kControlNonceEnabled) &&
(!CheckNonce(key_control_block.nonce()))) {
LOGE("KCB: BAD Nonce");
return OEMCrypto_ERROR_INVALID_NONCE;
}
content_key->UpdateDuration(key_control_block);
return OEMCrypto_SUCCESS;
}
bool SessionContext::DecryptRSAKey(const uint8_t* enc_rsa_key,
size_t enc_rsa_key_length,
const uint8_t* enc_rsa_key_iv,
uint8_t* pkcs8_rsa_key) {
// Decrypt rsa key with keybox.
uint8_t iv_buffer[wvcdm::KEY_IV_SIZE];
memcpy(iv_buffer, enc_rsa_key_iv, wvcdm::KEY_IV_SIZE);
AES_KEY aes_key;
AES_set_decrypt_key(&encryption_key_[0], 128, &aes_key);
AES_cbc_encrypt(enc_rsa_key, pkcs8_rsa_key, enc_rsa_key_length, &aes_key,
iv_buffer, AES_DECRYPT);
return true;
}
bool SessionContext::EncryptRSAKey(const uint8_t* pkcs8_rsa_key,
size_t enc_rsa_key_length,
const uint8_t* enc_rsa_key_iv,
uint8_t* enc_rsa_key) {
// Encrypt rsa key with keybox.
uint8_t iv_buffer[wvcdm::KEY_IV_SIZE];
memcpy(iv_buffer, enc_rsa_key_iv, wvcdm::KEY_IV_SIZE);
AES_KEY aes_key;
AES_set_encrypt_key(&encryption_key_[0], 128, &aes_key);
AES_cbc_encrypt(pkcs8_rsa_key, enc_rsa_key, enc_rsa_key_length, &aes_key,
iv_buffer, AES_ENCRYPT);
return true;
}
bool SessionContext::LoadRSAKey(const uint8_t* pkcs8_rsa_key,
size_t rsa_key_length) {
rsa_key_.reset();
if (rsa_key_length < 8) {
LOGE("[LoadRSAKey(): Very Short Buffer]");
return false;
}
if ((memcmp(pkcs8_rsa_key, "SIGN", 4) == 0)) {
uint32_t* schemes_n = (uint32_t*)(pkcs8_rsa_key + 4);
allowed_schemes_ = htonl(*schemes_n);
pkcs8_rsa_key += 8;
rsa_key_length -= 8;
} else {
allowed_schemes_ = kSign_RSASSA_PSS;
}
return rsa_key_.LoadPkcs8RsaKey(pkcs8_rsa_key, rsa_key_length);
}
OEMCryptoResult SessionContext::CheckKeyUse(const std::string& log_string,
uint32_t use_type,
OEMCryptoBufferType buffer_type) {
const KeyControlBlock& control = current_content_key()->control();
if (use_type && (!(control.control_bits() & use_type))) {
LOGE("[%s(): control bit says not allowed.", log_string.c_str());
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (control.control_bits() & kControlDataPathSecure) {
if (!ce_->config_closed_platform() &&
buffer_type == OEMCrypto_BufferType_Clear) {
LOGE("[%s(): Secure key with insecure buffer]", log_string.c_str());
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
}
if (control.control_bits() & kControlReplayMask) {
if (!CheckUsageEntry()) {
LOGE("[%s(): usage entry not valid]", log_string.c_str());
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
}
if (control.duration() > 0) {
if (control.duration() < CurrentTimer()) {
LOGE("[%s(): key expired.", log_string.c_str());
return OEMCrypto_ERROR_KEY_EXPIRED;
}
}
if (!ce_->config_local_display_only()) {
// Only look at HDCP and Analog restrictions if the display can be
// non-local.
if (control.control_bits() & kControlHDCPRequired) {
uint8_t required_hdcp =
(control.control_bits() & kControlHDCPVersionMask) >>
kControlHDCPVersionShift;
if (ce_->srm_blacklisted_device_attached()) {
required_hdcp = HDCP_NO_DIGITAL_OUTPUT;
}
// For reference implementation, we pretend we can handle the current
// HDCP version.
if (required_hdcp > ce_->config_current_hdcp_capability() ||
ce_->config_current_hdcp_capability() == 0) {
return OEMCrypto_ERROR_INSUFFICIENT_HDCP;
}
}
}
if (!ce_->config_local_display_only() ||
buffer_type == OEMCrypto_BufferType_Clear) {
if (control.control_bits() & kControlDisableAnalogOutput) {
LOGE("[%s(): control bit says disable analog.", log_string.c_str());
return OEMCrypto_ERROR_ANALOG_OUTPUT;
}
}
return OEMCrypto_SUCCESS;
}
OEMCryptoResult SessionContext::Generic_Encrypt(const uint8_t* in_buffer,
size_t buffer_length,
const uint8_t* iv,
OEMCrypto_Algorithm algorithm,
uint8_t* out_buffer) {
// Check there is a content key
if (current_content_key() == NULL) {
LOGE("[Generic_Encrypt(): OEMCrypto_ERROR_NO_CONTENT_KEY]");
return OEMCrypto_ERROR_NO_CONTENT_KEY;
}
const std::vector<uint8_t>& key = current_content_key()->value();
// Set the AES key.
if (static_cast<int>(key.size()) != AES_BLOCK_SIZE) {
LOGE("[Generic_Encrypt(): CONTENT_KEY has wrong size: %d", key.size());
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
OEMCryptoResult result = CheckKeyUse("Generic_Encrypt", kControlAllowEncrypt,
OEMCrypto_BufferType_Clear);
if (result != OEMCrypto_SUCCESS) return result;
if (algorithm != OEMCrypto_AES_CBC_128_NO_PADDING) {
LOGE("[Generic_Encrypt(): algorithm bad.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (buffer_length % AES_BLOCK_SIZE != 0) {
LOGE("[Generic_Encrypt(): buffers size bad.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
const uint8_t* key_u8 = &key[0];
AES_KEY aes_key;
if (AES_set_encrypt_key(key_u8, AES_BLOCK_SIZE * 8, &aes_key) != 0) {
LOGE("[Generic_Encrypt(): FAILURE]");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
uint8_t iv_buffer[wvcdm::KEY_IV_SIZE];
memcpy(iv_buffer, iv, wvcdm::KEY_IV_SIZE);
AES_cbc_encrypt(in_buffer, out_buffer, buffer_length, &aes_key, iv_buffer,
AES_ENCRYPT);
return OEMCrypto_SUCCESS;
}
OEMCryptoResult SessionContext::Generic_Decrypt(const uint8_t* in_buffer,
size_t buffer_length,
const uint8_t* iv,
OEMCrypto_Algorithm algorithm,
uint8_t* out_buffer) {
// Check there is a content key
if (current_content_key() == NULL) {
LOGE("[Generic_Decrypt(): OEMCrypto_ERROR_NO_CONTENT_KEY]");
return OEMCrypto_ERROR_NO_CONTENT_KEY;
}
const std::vector<uint8_t>& key = current_content_key()->value();
// Set the AES key.
if (static_cast<int>(key.size()) != AES_BLOCK_SIZE) {
LOGE("[Generic_Decrypt(): CONTENT_KEY has wrong size.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
OEMCryptoResult result = CheckKeyUse("Generic_Decrypt", kControlAllowDecrypt,
OEMCrypto_BufferType_Clear);
if (result != OEMCrypto_SUCCESS) return result;
if (algorithm != OEMCrypto_AES_CBC_128_NO_PADDING) {
LOGE("[Generic_Decrypt(): bad algorithm.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (buffer_length % AES_BLOCK_SIZE != 0) {
LOGE("[Generic_Decrypt(): bad buffer size.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
const uint8_t* key_u8 = &key[0];
AES_KEY aes_key;
if (AES_set_decrypt_key(key_u8, AES_BLOCK_SIZE * 8, &aes_key) != 0) {
LOGE("[Generic_Decrypt(): FAILURE]");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
uint8_t iv_buffer[wvcdm::KEY_IV_SIZE];
memcpy(iv_buffer, iv, wvcdm::KEY_IV_SIZE);
AES_cbc_encrypt(in_buffer, out_buffer, buffer_length, &aes_key, iv_buffer,
AES_DECRYPT);
return OEMCrypto_SUCCESS;
}
OEMCryptoResult SessionContext::Generic_Sign(const uint8_t* in_buffer,
size_t buffer_length,
OEMCrypto_Algorithm algorithm,
uint8_t* signature,
size_t* signature_length) {
// Check there is a content key
if (current_content_key() == NULL) {
LOGE("[Generic_Sign(): OEMCrypto_ERROR_NO_CONTENT_KEY]");
return OEMCrypto_ERROR_NO_CONTENT_KEY;
}
if (*signature_length < SHA256_DIGEST_LENGTH) {
*signature_length = SHA256_DIGEST_LENGTH;
LOGE("[Generic_Sign(): bad signature length.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
const std::vector<uint8_t>& key = current_content_key()->value();
if (static_cast<int>(key.size()) != SHA256_DIGEST_LENGTH) {
LOGE("[Generic_Sign(): CONTENT_KEY has wrong size; %d", key.size());
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
OEMCryptoResult result = CheckKeyUse("Generic_Sign", kControlAllowSign,
OEMCrypto_BufferType_Clear);
if (result != OEMCrypto_SUCCESS) return result;
if (algorithm != OEMCrypto_HMAC_SHA256) {
LOGE("[Generic_Sign(): bad algorithm.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
unsigned int md_len = *signature_length;
if (HMAC(EVP_sha256(), &key[0], key.size(), in_buffer, buffer_length,
signature, &md_len)) {
*signature_length = md_len;
return OEMCrypto_SUCCESS;
}
LOGE("[Generic_Sign(): hmac failed.");
dump_openssl_error();
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
OEMCryptoResult SessionContext::Generic_Verify(const uint8_t* in_buffer,
size_t buffer_length,
OEMCrypto_Algorithm algorithm,
const uint8_t* signature,
size_t signature_length) {
// Check there is a content key
if (current_content_key() == NULL) {
LOGE("[Decrypt_Verify(): OEMCrypto_ERROR_NO_CONTENT_KEY]");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
if (signature_length < SHA256_DIGEST_LENGTH) {
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
const std::vector<uint8_t>& key = current_content_key()->value();
if (static_cast<int>(key.size()) != SHA256_DIGEST_LENGTH) {
LOGE("[Generic_Verify(): CONTENT_KEY has wrong size: %d", key.size());
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
OEMCryptoResult result = CheckKeyUse("Generic_Verify", kControlAllowVerify,
OEMCrypto_BufferType_Clear);
if (result != OEMCrypto_SUCCESS) return result;
if (algorithm != OEMCrypto_HMAC_SHA256) {
LOGE("[Generic_Verify(): bad algorithm.");
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
unsigned int md_len = signature_length;
uint8_t computed_signature[SHA256_DIGEST_LENGTH];
if (HMAC(EVP_sha256(), &key[0], key.size(), in_buffer, buffer_length,
computed_signature, &md_len)) {
if (0 == memcmp(signature, computed_signature, SHA256_DIGEST_LENGTH)) {
return OEMCrypto_SUCCESS;
} else {
return OEMCrypto_ERROR_SIGNATURE_FAILURE;
}
}
LOGE("[Generic_Verify(): HMAC failed.");
dump_openssl_error();
return OEMCrypto_ERROR_UNKNOWN_FAILURE;
}
bool SessionContext::UpdateMacKeys(const std::vector<uint8_t>& enc_mac_keys,
const std::vector<uint8_t>& iv) {
// Decrypt mac key from enc_mac_key using device_keya
std::vector<uint8_t> mac_keys;
if (!DecryptMessage(encryption_key_, iv, enc_mac_keys, &mac_keys)) {
return false;
}
mac_key_server_ = std::vector<uint8_t>(
mac_keys.begin(), mac_keys.begin() + wvcdm::MAC_KEY_SIZE);
mac_key_client_ = std::vector<uint8_t>(mac_keys.begin() + wvcdm::MAC_KEY_SIZE,
mac_keys.end());
return true;
}
bool SessionContext::QueryKeyControlBlock(const KeyId& key_id, uint32_t* data) {
const Key* content_key = session_keys_.Find(key_id);
if (LogCategoryEnabled(kLoggingTraceDecryption)) {
LOGI(("Select Key: key_id = " + wvcdm::b2a_hex(key_id)).c_str());
if (content_key) {
LOGI(("Select Key: key = " + wvcdm::b2a_hex(content_key->value()))
.c_str());
} else {
LOGI("Select Key: key = null.");
}
}
if (NULL == content_key) {
LOGE("[QueryKeyControlBlock(): No key matches key id]");
return false;
}
data[0] = 0; // verification optional.
data[1] = htonl(content_key->control().duration());
data[2] = 0; // nonce optional.
data[3] = htonl(content_key->control().control_bits());
return true;
}
OEMCryptoResult SessionContext::SelectContentKey(const KeyId& key_id) {
const Key* content_key = session_keys_.Find(key_id);
if (LogCategoryEnabled(kLoggingTraceDecryption)) {
LOGI((" Select Key: key_id = " + wvcdm::b2a_hex(key_id)).c_str());
LOGI((" Select Key: key = " + wvcdm::b2a_hex(content_key->value()))
.c_str());
}
if (NULL == content_key) {
LOGE("[SelectContentKey(): No key matches key id]");
return OEMCrypto_ERROR_NO_CONTENT_KEY;
}
current_content_key_ = content_key;
const KeyControlBlock& control = current_content_key()->control();
if (control.duration() > 0) {
if (control.duration() < CurrentTimer()) {
LOGE("[SelectContentKey(): KEY_EXPIRED %d versus %d]",
control.duration(), CurrentTimer());
return OEMCrypto_ERROR_KEY_EXPIRED;
}
}
return OEMCrypto_SUCCESS;
}
void SessionContext::AddNonce(uint32_t nonce) { nonce_table_.AddNonce(nonce); }
bool SessionContext::CheckNonce(uint32_t nonce) {
return nonce_table_.CheckNonce(nonce);
}
void SessionContext::FlushNonces() { nonce_table_.Flush(); }
bool SessionContext::CheckUsageEntry() {
if (!usage_entry_) return false;
return usage_entry_->CheckForUse();
}
OEMCryptoResult SessionContext::CreateNewUsageEntry(
uint32_t* usage_entry_number) {
OEMCryptoResult result = ce_->usage_table().CreateNewUsageEntry(
this, &usage_entry_, usage_entry_number);
if (usage_entry_) {
usage_entry_status_ = kUsageEntryNew;
}
return result;
}
OEMCryptoResult SessionContext::LoadUsageEntry(
uint32_t index, const std::vector<uint8_t>& buffer) {
OEMCryptoResult result =
ce_->usage_table().LoadUsageEntry(this, &usage_entry_, index, buffer);
if (usage_entry_) {
usage_entry_status_ = kUsageEntryLoaded;
}
return result;
}
OEMCryptoResult SessionContext::UpdateUsageEntry(uint8_t* header_buffer,
size_t* header_buffer_length,
uint8_t* entry_buffer,
size_t* entry_buffer_length) {
if (!usage_entry_) {
LOGE("UpdateUsageEntry: Session has no entry.");
return OEMCrypto_ERROR_INVALID_CONTEXT;
}
return ce_->usage_table().UpdateUsageEntry(this, usage_entry_, header_buffer,
header_buffer_length, entry_buffer,
entry_buffer_length);
}
OEMCryptoResult SessionContext::DeactivateUsageEntry(
const std::vector<uint8_t>& pst) {
if (!usage_entry_) return OEMCrypto_ERROR_INVALID_CONTEXT;
usage_entry_->Deactivate(pst);
return OEMCrypto_SUCCESS;
}
OEMCryptoResult SessionContext::ReportUsage(const std::vector<uint8_t>& pst,
uint8_t* buffer,
size_t* buffer_length) {
if (!usage_entry_) return OEMCrypto_ERROR_INVALID_CONTEXT;
return usage_entry_->ReportUsage(pst, buffer, buffer_length);
}
OEMCryptoResult SessionContext::MoveEntry(uint32_t new_index) {
if (!usage_entry_) return OEMCrypto_ERROR_INVALID_CONTEXT;
return ce_->usage_table().MoveEntry(usage_entry_, new_index);
}
OEMCryptoResult SessionContext::CopyOldUsageEntry(
const std::vector<uint8_t>& pst) {
if (!usage_entry_) return OEMCrypto_ERROR_INVALID_CONTEXT;
return usage_entry_->CopyOldUsageEntry(pst);
}
// Internal utility function to decrypt the message
bool SessionContext::DecryptMessage(const std::vector<uint8_t>& key,
const std::vector<uint8_t>& iv,
const std::vector<uint8_t>& message,
std::vector<uint8_t>* decrypted) {
if (key.empty() || iv.empty() || message.empty() || !decrypted) {
LOGE("[DecryptMessage(): OEMCrypto_ERROR_INVALID_CONTEXT]");
return false;
}
decrypted->resize(message.size());
uint8_t iv_buffer[16];
memcpy(iv_buffer, &iv[0], 16);
AES_KEY aes_key;
AES_set_decrypt_key(&key[0], 128, &aes_key);
AES_cbc_encrypt(&message[0], &(decrypted->front()), message.size(), &aes_key,
iv_buffer, AES_DECRYPT);
return true;
}
OEMCryptoResult SessionContext::DecryptCENC(
const uint8_t* iv, size_t block_offset,
const OEMCrypto_CENCEncryptPatternDesc* pattern, const uint8_t* cipher_data,
size_t cipher_data_length, bool is_encrypted, uint8_t* clear_data,
OEMCryptoBufferType buffer_type) {
// If the data is clear, we do not need a current key selected.
if (!is_encrypted) {
if (buffer_type != OEMCrypto_BufferType_Direct) {
memcpy(reinterpret_cast<uint8_t*>(clear_data), cipher_data,
cipher_data_length);
return OEMCrypto_SUCCESS;
}
// For reference implementation, we quietly drop the clear direct video.
return OEMCrypto_SUCCESS;
}
// Check there is a content key
if (current_content_key() == NULL) {
LOGE("[DecryptCTR(): OEMCrypto_ERROR_NO_CONTENT_KEY]");
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
OEMCryptoResult result = CheckKeyUse("DecryptCENC", 0, buffer_type);
if (result != OEMCrypto_SUCCESS) return result;
const std::vector<uint8_t>& content_key = current_content_key()->value();
// Set the AES key.
if (static_cast<int>(content_key.size()) != AES_BLOCK_SIZE) {
LOGE("[DecryptCTR(): CONTENT_KEY has wrong size: %d", content_key.size());
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
const uint8_t* key_u8 = &content_key[0];
if (buffer_type == OEMCrypto_BufferType_Direct) {
// For reference implementation, we quietly drop the decrypted direct video.
return OEMCrypto_SUCCESS;
}
if (!current_content_key()->ctr_mode()) {
if (block_offset > 0) return OEMCrypto_ERROR_INVALID_CONTEXT;
return DecryptCBC(key_u8, iv, pattern, cipher_data, cipher_data_length,
clear_data);
}
if (pattern->skip > 0) {
return PatternDecryptCTR(key_u8, iv, block_offset, pattern, cipher_data,
cipher_data_length, clear_data);
}
return DecryptCTR(key_u8, iv, block_offset, cipher_data, cipher_data_length,
clear_data);
}
OEMCryptoResult SessionContext::DecryptCBC(
const uint8_t* key, const uint8_t* initial_iv,
const OEMCrypto_CENCEncryptPatternDesc* pattern, const uint8_t* cipher_data,
size_t cipher_data_length, uint8_t* clear_data) {
AES_KEY aes_key;
AES_set_decrypt_key(&key[0], AES_BLOCK_SIZE * 8, &aes_key);
uint8_t iv[AES_BLOCK_SIZE];
uint8_t next_iv[AES_BLOCK_SIZE];
memcpy(iv, &initial_iv[0], AES_BLOCK_SIZE);
size_t l = 0;
size_t pattern_offset = pattern->offset;
while (l < cipher_data_length) {
size_t size =
std::min(cipher_data_length - l, static_cast<size_t>(AES_BLOCK_SIZE));
size_t pattern_length = pattern->encrypt + pattern->skip;
bool skip_block =
(pattern_offset >= pattern->encrypt) && (pattern_length > 0);
if (pattern_length > 0) {
pattern_offset = (pattern_offset + 1) % pattern_length;
}
if (skip_block || (size < AES_BLOCK_SIZE)) {
memcpy(&clear_data[l], &cipher_data[l], size);
} else {
uint8_t aes_output[AES_BLOCK_SIZE];
// Save the iv for the next block, in case cipher_data is in the same
// buffer as clear_data.
memcpy(next_iv, &cipher_data[l], AES_BLOCK_SIZE);
AES_decrypt(&cipher_data[l], aes_output, &aes_key);
for (size_t n = 0; n < AES_BLOCK_SIZE; n++) {
clear_data[l + n] = aes_output[n] ^ iv[n];
}
memcpy(iv, next_iv, AES_BLOCK_SIZE);
}
l += size;
}
return OEMCrypto_SUCCESS;
}
OEMCryptoResult SessionContext::PatternDecryptCTR(
const uint8_t* key, const uint8_t* initial_iv, size_t block_offset,
const OEMCrypto_CENCEncryptPatternDesc* pattern, const uint8_t* cipher_data,
size_t cipher_data_length, uint8_t* clear_data) {
AES_KEY aes_key;
AES_set_encrypt_key(&key[0], AES_BLOCK_SIZE * 8, &aes_key);
uint8_t iv[AES_BLOCK_SIZE];
memcpy(iv, &initial_iv[0], AES_BLOCK_SIZE);
size_t l = 0;
size_t pattern_offset = pattern->offset;
while (l < cipher_data_length) {
size_t size =
std::min(cipher_data_length - l, AES_BLOCK_SIZE - block_offset);
size_t pattern_length = pattern->encrypt + pattern->skip;
bool skip_block =
(pattern_offset >= pattern->encrypt) && (pattern_length > 0);
if (pattern_length > 0) {
pattern_offset = (pattern_offset + 1) % pattern_length;
}
if (skip_block) {
memcpy(&clear_data[l], &cipher_data[l], size);
} else {
uint8_t aes_output[AES_BLOCK_SIZE];
AES_encrypt(iv, aes_output, &aes_key);
for (size_t n = 0; n < size; n++) {
clear_data[l + n] = aes_output[n + block_offset] ^ cipher_data[l + n];
}
ctr128_inc64(iv);
}
l += size;
block_offset = 0;
}
return OEMCrypto_SUCCESS;
}
// This is a special case of PatternDecryptCTR with no skip pattern. It uses
// more optimized versions of openssl's implementation of AES CTR mode.
OEMCryptoResult SessionContext::DecryptCTR(const uint8_t* key_u8,
const uint8_t* iv,
size_t block_offset,
const uint8_t* cipher_data,
size_t cipher_data_length,
uint8_t* clear_data) {
// Local copy (will be modified).
// Allocated as 64-bit ints to enforce 64-bit alignment for later access as a
// 64-bit value.
uint64_t aes_iv[2];
assert(sizeof(aes_iv) == AES_BLOCK_SIZE);
// The double-cast is needed to comply with strict aliasing rules.
uint8_t* aes_iv_u8 =
reinterpret_cast<uint8_t*>(reinterpret_cast<void*>(aes_iv));
memcpy(aes_iv_u8, &iv[0], AES_BLOCK_SIZE);
// The CENC spec specifies we increment only the low 64 bits of the IV
// counter, and leave the high 64 bits alone. This is different from the
// OpenSSL implementation, which increments the entire 128 bit iv. That is
// why we implement the CTR loop ourselves.
size_t l = 0;
if (block_offset > 0 && l < cipher_data_length) {
// Encrypt the IV.
uint8_t ecount_buf[AES_BLOCK_SIZE];
AES_KEY aes_key;
if (AES_set_encrypt_key(key_u8, AES_BLOCK_SIZE * 8, &aes_key) != 0) {
LOGE("[DecryptCTR(): FAILURE]");
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
AES_encrypt(aes_iv_u8, ecount_buf, &aes_key);
for (int n = block_offset; n < AES_BLOCK_SIZE && l < cipher_data_length;
++n, ++l) {
clear_data[l] = cipher_data[l] ^ ecount_buf[n];
}
ctr128_inc64(aes_iv_u8);
block_offset = 0;
}
uint64_t remaining = cipher_data_length - l;
int out_len = 0;
while (remaining) {
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX_init(&ctx);
EVP_CIPHER_CTX_set_padding(&ctx, 0);
if (!EVP_DecryptInit_ex(&ctx, EVP_aes_128_ctr(), NULL, key_u8, aes_iv_u8)) {
LOGE("[DecryptCTR(): EVP_INIT ERROR]");
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
// Test the MSB of the counter portion of the initialization vector. If the
// value is 0xFF the counter is near wrapping. In this case we calculate
// the number of bytes we can safely decrypt before the counter wraps.
uint64_t decrypt_length = 0;
if (aes_iv_u8[8] == 0xFF) {
uint64_t bottom_64_bits = wvcdm::ntohll64(aes_iv[1]);
uint64_t bytes_before_iv_wrap = (~bottom_64_bits + 1) * AES_BLOCK_SIZE;
decrypt_length =
bytes_before_iv_wrap < remaining ? bytes_before_iv_wrap : remaining;
} else {
decrypt_length = remaining;
}
if (!EVP_DecryptUpdate(&ctx, &clear_data[l], &out_len, &cipher_data[l],
decrypt_length)) {
LOGE("[DecryptCTR(): EVP_UPDATE_ERROR]");
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
l += decrypt_length;
remaining = cipher_data_length - l;
int final;
if (!EVP_DecryptFinal_ex(
&ctx, &clear_data[cipher_data_length - remaining], & final)) {
LOGE("[DecryptCTR(): EVP_FINAL_ERROR]");
return OEMCrypto_ERROR_DECRYPT_FAILED;
}
EVP_CIPHER_CTX_cleanup(&ctx);
// If remaining is not zero, reset the iv before the second pass.
if (remaining) {
memcpy(aes_iv_u8, &iv[0], AES_BLOCK_SIZE);
memset(&aes_iv_u8[8], 0, AES_BLOCK_SIZE / 2);
}
}
return OEMCrypto_SUCCESS;
}
} // namespace wvoec_mock
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